24hp briggs engine

[mcwh5555]

I have a craftman riding mower with 24hp briggs engine that starts to pop like a back fire sound after running for about 20 minutes , mower still runs good ?? Thanks !!

 

[reynoldston]

sound like a tight valve?

 

[motoman]

My only experience is with the Intek 24. I would pop the valve covers and check clearances. Then I would carefully watch the lift of the exhaust valves as you turn over the engine by hand. Take off the screen , remove plugs, turn flywheel by hand. Look through the valve springs at the valve guides to determine if any (exhaust guide) is "on the move upwards." If so one will protrude upward further than the other. Mine was starter side

If the guides have slowly moved upward (due to overheat) the cam lobe has slowly ground away. If this has happened , eventually only one cylinder will fire. (Whole horror story elsewhere in this forum) Good luck :smiley_aafz:

 

[chance123]

Compare the 2 spk plgs. Spk plgs show the health of the engine. Let us know the differences in color.